On the reactions of methyl radicals with nitrilotris(methylenephosphonic-acid) complexes in aqueous solutions

Abstract

The reactions of methyl radicals with M^II-(ntp)(H₂O)₂ complexes were studied. The formation of an unstable intermediate (ntp)(H₂O)M^III-CH₃ is observed. This reaction is an equilibrium process, i.e. the M^III-C bond decomposes via homolysis. The (ntp)(H₂O)M^III-CH₃ complexes isomerize to a more stable form. The results compared to those obtained in analogous reactions of the M^II-(nta)(H₂O)₂ complexes were shown to be similar with one exception – for the nta complexes no isomerization process is observed.     

Preparation and phase relationships in systems of the type CdSMIMIIIS2 where MI = Ag,Cu and MIII = Al,Ga, In

Systems of the type M^IM^IIIS₂ (chalcopyrite)-CdS (wurtzite) where M^I = Ag, Cu and M^III = Al, Ga, In were investigated to determine the regions of mutual solid solubility. It was found that the chalcopyrite structure could not tolerate extensive CdS substitution. When M^III was Al or Ga the solubility of M^IM^IIIS₂ in CdS was also very limited. However, when M^III = In (r_In³⁺ ? r_Ga³⁺ > r_Al³⁺), the solubility of M^IInS₂ in CdS was quite extensive (～50%). These results are consistent with a prior study on systems of the type M^IM^IIIS₂ZnS which indicated that in sulfides, larger cations tend to result in the formation of new quaternary, wurtzite phases.     

Synthesis,structures, IR spectra,and thermal characteristics of compounds of general formula Ba(M<Stack><Subscript>2/3</Subscript><Superscript>III</Superscript></Stack>U<Subscript>1/3</Subscript>)O<Subscript>3</Subscript> (M<Superscript>III</Superscript> = Sc,Y, In,Nd-Lu)

Compounds with the composition Ba(M _2/3 ^III U_1/3)O₃ (M^III = Sc, Y, In, Nd-Lu) were synthesized by high-temperature solid-state reactions. The structures of the compounds were studied by X-ray diffraction analysis, including the high-temperature method, and IR spectroscopy.     

Strukturuntersuchungen an Usoviten: Ba2CaMIIV2F14 (MIII = Mn,Fe), Ba2CaMnFe2F14 und Ba2CaCuM2IIIF14 (MIII = Mn,Fe, Ga)

Structural Studies with Usovites: Ba₂CaM^IIV₂F₁₄ (M^III = Mn, Fe), Ba₂CaMnFe₂F₁₄ and Ba₂CaCuM₂^IIIF₁₄ (M^III = Mn, Fe, Ga). Single crystals of six compounds Ba₂CaM^IIM₂^IIIF₁₄ were prepared to refine their usovite type structure (space group C2/c, Z = 4) using X‐ray diffractometer data. The cell parameters of the phases studied with M^IIM₂^III= MnV₂, FeV₂, CuMn₂, MnFe₂, CuFe₂ und CuGa₂ are within the range 1374≤a/pm≤1384, 534≤b/pm≤542, 1474≤c/pm≤1510, 91, 3≤ß/°≤93, 2. The atoms Ca and M^II are incompletely ordered on the 8‐ and 6‐coordinated positions, 4e and 4b, respectively. In the case of Ba₂CaFeV₂F₁₄ and Ba₂CaCuGa₂F₁₄ there is reciprocal substitution (x≈0, 1): (Ca_1‐xM_x^II) (4e) and (M_1‐x^IICa_x) (4b). In the case of the other usovites Ca‐enriched phases Ba₂Ca(M_1‐y^IICa_y)M₂^IIIF₁₄ occured (up to y≈0, 35), exhibiting partial substitution at the octahedral position (4b) only, showing a corresponding increase in M^II‐F distances. The distortion of [M^IIF₆] and [M^IIIF₆] octahedra within the structure is considerably enhanced on replacement by Cu^II and Mn^III. The results of powder magnetic susceptibility measurements of Ba₂CaMnV₂F₁₄ and Ba₂CaFeV₂F₁₄ (T_N≈7K) are reported.     

Synthesis, structure, and magnetic properties of heterometallic trinuclear complexes {MII��LnIII��MII} (MII = Ni, Cu; LnIII = La, Pr, Sm, Eu, Gd)

Trinuclear heterometallic complexes containing the {M₂Ln(Piv)₆(NO₃)} (M^II = Ni, Cu; Ln^III = Nd, Pr, Sm, Eu, Gd; Piv^? is the anion of pivalic acid) and {Cu₂Ln(Piv)₈)]^? (Ln^III = Eu, Gd) metal cores were synthesized, their structures and magnetic properties were studied. For the most compounds, it was shown that their magnetic properties can be interpreted taking no interaction of the 3d-metal ions and a lanthanide into account. Ferromagnetic exchange interactions were found to exist between the unpaired electrons of the paramagnetic centers in the exchange clusters of the gadolinium-containing heterometallic complexes {M-Gd-M} (M = Ni or Cu).     

Untersuchungen an quaternären Fluoriden LiMIIMIIIF6, Über die Kationenverteilung in Fluortrirutilen

Inhaltsübersicht. Fluortrirutile LiM^IIM^IIIF₆ kristallisieren tetragonal in dor Raumgruppe P4₂/mnm mit Li in Position (2a) und M^II und M^III statistisch vorteilt in (4e). An Einkristallen und durch Pulvermessungen wurde die Verteilung der Kationen untersucht, wozu die neu dargestellte Rhodiumverbindung LiZnRhF₆ auf Grund des unterschiedlichen Streuvermögens der Kationen besonders geeignet war. Verbindungen LiCuM^IIIF₆ zeigen die einfache Rutilstruktur. Investigations of the Quaternary Fluorides LiM^IIM^IIIF₆. On the Distribution of Cations in Fluorotrirutiles Abstract. Trirutiles LiM^IIM^IIIF₆ crystallize tetragonally in the space group P4₂/mnm with Li in position (2a) und M^II and M^III statistically distributed in (4e). By single-crystal X-Ray diffraction and by powder work cation ordering was examined for which the new compound LiZnRhF, was especially adapted. Compounds LiCuM^IIIF₆ are disordered rutile phases.     

Synthesis and crystal structure of new complex sodium lanthanide phosphate molybdates Na2MIII(MoO4)(PO4)(MIII = Tb, Dy, Ho, Er, Tm, Lu)

New complex sodium lanthanide phosphate molybdates Na₂M^III(MoO₄)(PO₄)(M^III=Tb, Dy, Ho, Er, Tm, Lu) have been synthesized by the ceramic method (T = 600°C, τ = 48 h), and their unit cell parameters have been determined. The structures of Na₂M^III(MoO₄)(PO₄)(M^III = Dy, Ho, Er, Lu) were refined by the Rietveld method. The compounds are isostructural: they are orthorhombic (space group Ibca, Z = 8) and have layered structures. In the structures of phosphate molybdates, chains of M^IIIO₈ polyhedra and MoO₄ tetrahedra are linked by PO₄ tetrahedra to form layers. The MoO ₄ ^2? anions are involved in dipole-dipole interaction. The sodium ions are arranged in the interlayer space. The compounds melt incongruently at 850–870°C.     

A Pedagogical Illustration of the Determination of the Nature and Strength of Bonds in Crystalline Compounds from X-ray Diffraction and Infrared Spectroscopy Studies

This article describes a method used to teach students how X-ray crystallography and infrared spectroscopy analysis can be used to obtain information about the nature and strength of the bonding in the crystalline compounds M^IM^III(SO₄)₂ (with M^I = K⁺, Rb⁺, Cs⁺ and M^III = Al³⁺, Cr³⁺, Fe³⁺). These sulfates form an isomorphic series. The influences of specific M^IM^III ions on the variation of the a and c parameters and on the position of IR absorption bands are described. Additionally, X-ray crystallography and infrared spectroscopy studies of the double sulfates M^IM^III(SO₄)₂ show students the existence of [SO₄-M^III-SO₄]^– layers in the crystallized products; the covalent character of M^III-O attractions, which give cohesion in these layers; the existence of M^I layers between [SO₄-M^III-SO₄]^– layers, and the electrovalent character of M^I-O interactions.     

Zur Kenntnis des Verhaltens der Oxidsulfate der Seltenen Erden gegen Chlorwasserstoff. II. Charakterisierung und thermisches Verhalten der Umsetzungsprodukte der Oxidsulfate mit Chlorwasserstoff

The reaction products of the oxide sulphates of rare earths with hydrogen chloride are mixtures of chlorides M^IIICl₃ and chloride-sulphates M^IIICl₃ and chloride-sulphates M^IIIClSO₄. By oxidation of these mixtures, oxide sulphates MO₂SO₄ are formed as final products. Intermediary products are mixtures of M^IIIOCl? M^IIIClSO₄.     

A New Domain of Reactivity for High‐Valent Dinuclear [M(μ‐O)2M′] Complexes in Oxidation Reactions

The strikingly different reactivity of a series of homo‐ and heterodinuclear [(M^III)(μ‐O)₂(M^III)′]²⁺ (M=Ni; M′=Fe, Co, Ni and M=M′=Co) complexes with β‐diketiminate ligands in electrophilic and nucleophilic oxidation reactions is reported, and can be correlated to the spectroscopic features of the [(M^III)(μ‐O)₂(M^III)′]²⁺ core. In particular, the unprecedented nucleophilic reactivity of the symmetric [Ni^III(μ‐O)₂Ni^III]²⁺ complex and the decay of the asymmetric [Ni^III(μ‐O)₂Co^III]²⁺ core through aromatic hydroxylation reactions represent a new domain for high‐valent bis(μ‐oxido)dimetal reactivity.     

Gitterkonstanten und Ionenradien für Pyrochlore CsMIIMIIIF6

Lattice Constants and Ionic Radii of Pyrochlores CsM^IIM^IIIF₆ From observed lattice constants a₀ of 30 cubic pyrochlores CsM^IIM^IIIF₆ (M^II = Mg, Ni, Cu, Zn, Co, Mn; M^III = Ga, Cr, Fe, V, Ti) balanced values a_c were calculated, which deviate in average less than 0.1% from the observed ones. Radii r_c of the M(II) and M(III) ions are evaluated from the balanced values a_c by means of an empiric equation; they reproduce the lattice constants a₀ equally well. By analogy derived radii r_II and r_III from additional pyrochlores CsM^IIM^IIIF₆ are given and discussed in comparison with tabulated radii and observed M? F distances.     

Über die Ordnung von BIII und MV in Perowskiten vom Typ ABIIIMVO6 (AII  Ba,Sr; MV  Sb,Nb, Ta)

On the Ordering of B^III and M^V in Perovskites of Type A B^IIIM^VO₆ (A^II ? Ba, Sr; M^V ? Sb, Nb, Ta) The perovskites Ba₂B^IIISbO₆ crystallize monoclinic (B^III ? La, Pr, Nd) and cubic (B^III ? Sm, Eu, Gd, Tb, Dy, Yb, Lu, Y) respectively. The Sr compounds, Sr₂B^IIISbO₆, have a monoclinic (B^III ? Nd, Sm, Eu, Dy), orthorhombic (B^III ? Yb, Lu, Y, Sc) or cubic (B^III ? In, Ga) perovskite structure. By intensity calculations and vibrational spectroscopic investigations deviations from a complete order between B^III and Sb^V are detectable. For perovskites Ba₂B^IIIM^VO₆ with M^V ? Nb, Ta the incompleteness of cationic order can be demonstrated as well.     

Cyano‐Bridged MnIII?MIII Single‐Chain Magnets with MIII=CoIII,FeIII, MnIII,and CrIII

A series of isostructural cyano‐bridged Mn^III(h.s.)–M^III(l.s.) alternating chains, [Mn^III(5‐TMAMsalen)M^III(CN)₆] ? 4H₂O (5‐TMAMsalen^2?=N,N′‐ethylenebis(5‐trimethylammoniomethylsalicylideneiminate), Mn^III(h.s.)=high‐spin Mn^III, M^III(l.s.)=low‐spin Co^III, Mn? Co ; Fe^III, Mn? Fe ; Mn^III, Mn? Mn ; Cr^III, Mn? Cr ) was synthesized by assembling [Mn^III(5‐TMAMsalen)]³⁺ and [M^III(CN)₆]^3?. The chains present in the four compounds, which crystallize in the monoclinic space group C2/c, are composed of an [‐Mn^III‐NC‐M^III‐CN‐] repeating motif, for which the ‐NC‐M^III‐CN‐ motif is provided by the [M^III(CN)₆]^3? moiety adopting a trans bridging mode between [Mn^III(5‐TMAMsalen)]³⁺ cations. The Mn^III and M^III ions occupy special crystallographic positions: a C₂ axis and an inversion center, respectively, forming a highly symmetrical chain with only one kind of cyano bridge. The Jahn–Teller axis of the Mn^III(h.s.) ion is perpendicular to the N₂O₂ plane formed by the 5‐TMAMsalen tetradentate ligand. These Jahn–Teller axes are all perfectly aligned along the unique chain direction without a bending angle, although the chains are corrugated with an Mn‐N_axis‐C angle of about 144°. In the crystal structures, the chains are well separated with the nearest inter‐chain M???M distance being relatively large at 9 Å due to steric hindrance of the bulky trimethylammoniomethyl groups of the 5‐TMAMsalen ligand. The magnetic properties of these compounds have been thoroughly studied. Mn? Fe and Mn? Mn display intra‐chain ferromagnetic interactions, whereas Mn? Cr is characterized by an antiferromagnetic exchange that induces a ferrimagnetic spin arrangement along the chain. Detailed analyses of both static and dynamic magnetic properties have demonstrated without ambiguity the single‐chain magnet (SCM) behavior of these three systems, whereas Mn? Co is merely paramagnetic with S_Mn=2 and D/k_B=?5.3 K (D being a zero‐field splitting parameter). At low temperatures, the Mn? M compounds with M=Fe, Mn, and Cr display remarkably large M versus H hysteresis loops for applied magnetic fields along the easy magnetic direction that corresponds to the chain direction. The temperature dependence of the associated relaxation time for this series of compounds systematically exhibits a crossover between two Arrhenius laws corresponding to infinite‐chain and finite‐chain regimes for the SCM behavior. These isostructural hetero‐spin SCMs offer a unique series of alternating [‐Mn‐NC‐M‐CN‐] chains, enabling physicists to test theoretical SCM models between the Ising and Heisenberg limits.     

Study of the trivalent elements polyphosphates by thermal analysis

Mechanisms of formation of polyphosphates Me^III(PO₃)₃, where M ^III=La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc, Fe, Ga, Al and Cr has been simulated by thermal analysis technique. Me^III oxides and ammonium dibasic phosphate (NH₄)₂HPO₄ were used as starting materials. For M ^III=La-Lu, Y and Fe three main stages were observed: 1. elimination of water and ammonia leading to the formation of ammonium tripolyphosphate (NH₄)₅P₃O₁₀; 2. reaction of the latter with Me₂^IIIO₃ and formation of acidic polyphosphates Me^IIIH₂P₃O₁₀ or their isomers Me^III(PO₃)₃·H₂O; 3. final loss of water and formation of Me^III(PO₃)₃. For Me ^III=Sc and Ga the second stage is prolonged and the polyphosphates form at higher temperatures. Aluminum and chromium polyphosphates are unstable. It is suggested that thermal behavior of the compounds is determined by Me^III ionic radii.     

Preparation and properties of the MIIIU2O7.5 polyuranates (MIII = Y,Tb, Dy,Ho, Er,Tm, Yb,or Lu)

The novel compounds of the M^IIIU₂O_7.5 type (with M^III being yttrium or lanthanides from terbium to lutetium) have been prepared via hydrothermal synthesis from hydrated uranium(VI) oxide and aqueous solutions of M(III) nitrates at 200°C. Composition and structure of the products have been studied by means of elemental analysis, high-temperature X-ray diffraction, and IR spectroscopy; the products thermal stability has been estimated.     

Mixed phosphates K2MIIIMV(OPO4)2: Heterovalence-substituted analogs of KTiOPO4

A series of heterovalence-substituted analogs of KTiOPO₄ of the general composition K₂M^IIIM^V(OPO₄)₂ (M^III = Cr, Fe, In; M^V = Nb, Ta) were synthesized by crystallization from melts and by solid-phase reactions. Influence of the nature of tri-and pentavalent metals on the conditions of preparation and on the features of phase formation of substituted mixed phosphates was examined. The compounds obtained were characterized by X-ray diffraction analysis and by diffuse reflection spectroscopy.     

IR- und Raman-Spektren einiger Kaliumpentafluorometallate-monohydrate

The IR- and Raman Spectra of several compounds of the stoichiometryM ₂ ^I M ^IIIF₅H₂O and their deuterated analogs have been interpreted on the basis of their crystal structures. The compounds studied were divided into two classes regarding the bonding of water molecules. The main spectroscopic difference between the two classes was found in the region of H₂O vibrations in good agreement with theoretical predictions. The metal—fluorine and metal—oxygene vibrations gave no direct information concerning the two types of water.     

IR-Spektren einiger hydratisierter Fluoro-aluminate,-gallate und-indate

Zusammenfassung Die Analyse der IR-Spektren einer Auswahl der Verbindungen des TypsM ₂ ^I M ^IIIF₅·H₂O bzw.M ^I M ^IIIF₄·2 H₂O und der entsprechenden Deuterohydrate führt zum Ergebnis, daß das Wasser nicht koordinativ gebunden, sondern als Gitterwasser auftritt. Bei den hydratisierten Fluorogallaten ist die Wasserstoffbindung stärker ausgeprägt als bei den entsprechenden Fluoro-aluminaten und-indaten.

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Fluoro metallates (III), IV: IR-Spectra of some hydrated fluoro-aluminates,-gallates, and-indates

Interpretation of the IR spectra of several compounds of the stoichiometryM ₂ ^I M ^IIIF₅·H₂O,M ^I M ^IIIF₄·2H₂O and their deuterated analogs proves the presence of the lattice water. Hydrogen bond is stronger in the case of fluorogallates in comparision to the similar fluoroaluminates and indates.

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3. Mitt.: Mh. Chem.102, 885 (1971).     

Pressure versus Temperature Effects on Intramolecular Electron Transfer in Mixed‐Valence Complexes

Mixed‐valence trinuclear carboxylates, [M₃O(O₂CR)₆L₃] (M=metal, L=terminal ligand), have small differences in potential energy between the configurations M^IIM^IIIM^III?? M^IIIM^IIM^III??M^IIIM^IIIM^II, which means that small external changes can have large structural effects, owing to the differences in coordination geometry between M²⁺ and M³⁺ sites (e.g., about 0.2 Å for Fe? O bond lengths). It is well‐established that the electron transfer (ET) between the metal sites in these mixed‐valence molecules is strongly dependent on temperature and on the specific crystal environment; however, herein, for the first time, we examine the effect of pressure on the electron transfer. Based on single‐crystal X‐ray diffraction data that were measured at 15, 90, 100, 110, 130, 160, and 298 K on three different crystals, we first unexpectedly found that our batch of Fe₃O (O₂CC(CH₃)₃)₆(C₅H₅N)₃ ( 1 ) exhibited a different temperature dependence of the ET process than previous studies of compound 1 have shown. We observed a phase transition at around 130 K that was related to complete valence trapping and Hirshfeld surface analysis revealed that this phase transition was governed by a subtle competition between C? H???π and π???π intermolecular interactions. Subsequent high‐pressure single‐crystal X‐ray diffraction at pressures of 0.15, 0.35, 0.45, 0.74, and 0.96 GPa revealed that it was not possible to trigger the phase transition (i.e., valence trapping) by a reduction of the unit‐cell volume, owing to this external pressure. We conclude that modulation of the ET process requires anisotropic changes in the intermolecular interactions, which occur when various directional chemical bonds are affected differently by changes in temperature, but not by the application of pressure.     

Ordre local dans quelques verres fluores du systeme PbF2MIItF2MIIItF3 par EXAFS

The local environment of transition metal (M_t) and lead has been studied by EXAFS for some fluoride glasses in the system PbF₂M^II_tF₂M^III_tF₃ (M^II_t = Mn²⁺, Zn²⁺; M^III_t = Fe³⁺, Ga³⁺). Theoretical phase shifts and backscattering amplitude are used after testing with crystallized fluorides of various structures. Transition metals are sixfold coordinated and M_tF distances are very close to those known in crystallized compounds. Lead has eight to nine fluorine neighbors forming a very distorted polyhedra. Radial distributions, partially corrected for phase shifts, show a very weak second peak but the second neighbors nature and the distances cannot be determined without ambiguity.